Nc sliding table control factors are three

3.1 stroke control General hydraulic sliding table and mechanical sliding table of the stroke control is to use position or pressure sensor (travel switch/die block iron) to realize the; And CNC sliding table stroke, the use of the digital control to rotating joints
By the nc sliding table structure, it is known that the sliding table stroke is proportional to the stepping motor of total Angle, so as long as control stepping motor of total Angle can be. By stepping motor work principle and characteristic that the stepping motor of total Angle is proportional to the input control pulse number; So it can be according to the servo mechanism to determine displacement PLC output pulse number: N = DL/d

(1) Type of DL - servo the displacement (mm), d - servo mechanism of pulse equivalent (mm/pulse) 3.2 feed speed control Servo feed speed depends on the stepping motor speed, and stepping motor speed depends on the input pulse frequency; So it can be according to rotary union the process requirements of the feed speed, determine its PLC output pulse frequency: F = Vf / 60 d (Hz)

(2) Type of Vf - servo feed speed (mm/min) 3.3 direction of feed control Direction of feed control is the step motor steering control. The step motor steering by changing the stepping motor the winding energizing order to change its steering; Such as three-phase stepper motor power on order for A - AB - B - BC - C - CA - A... When stepping motor is turn; When winding according to A - AC - C - CB - B - BA - A... Order is energized the stepping motor reversal. So it can be through the PLC output direction control signal change hardware circuit distributor output sequence to achieve, or the programming change output pulse sequence to change the stepping motor winding energizing order to realize. 4 PLC software control logic By sliding table PLC control method, it is known that should make stepping motor input pulse total number and pulse frequency by corresponding control. So in the control software establishment of a total number of pulse and pulse frequency controllable pulse signal generator; For low frequency control pulse, can use the timer PLC form, as shown in figure 2 shows. Pulse frequency can through the timer timing constant control pulse cycle, pulse total control, can set a pulse counter C10. When the pulse number to set value, counter C10 action to cut off the pulse generator circuit, make its stop working. Servo stepping motor no pulse input will stop running, servo actuator location. When servo actuator displacement speed when the demand is higher, can use the PLC high-speed pulse generator. Different PLC the high-speed pulse frequency can reach 4000 ~ 6000 hz. For the automatic production line of the general servo mechanism, its speed can get fully satisfy. Figure 2 5 servo control, drive and interface 5.1 stepping motor control system composition Stepping motor control system consists of PLC (programmable logic controller), round pulse distributor and stepping motor power drive component, the structure see figure 1. PLC control system used to generate control pulse;

Through the PLC programming output a certain number of square wave pulse, control the stepping motor of the corner and then control servo feed; At the same time through the programming control pulse frequency, both servo feed speed; Circular pulse distributor will be programmable controller output control pulse according to the step motor power on sequence distribution to the corresponding winding. PLC control stepping motor can use software circular distributor, also can use as shown in figure 1 shows hardware circuit distributor.

Adopting soft ring occupancy PLC more resources, especially the stepping motor winding phase M > 4, for large production line should be fully considered. The hardware circuits distributor, although the hardware structure a little trickier, but can save occupancy PLC I/O port points, at present the market has a variety of special chip can be chosen. Stepping motor power drive will PLC output control pulse amplification to fiber optic rotary joint dozens of ~ hundreds of volt, a few Ann ~ 10 Ann's driving ability. General PLC output interface has certain ability for drive, and ordinary transistor dc output interface of the load capacity is only 10 ~ dozens of volts, dozens of ~ hundreds of ma.
But for power stepping motor calls for decades to hundreds of volt, a few Ann ~ 10 Ann's driving ability and should, therefore, the drive to output pulse of amplification.